Bis(substituted thioalkyl)hydroxylamines and stabilized polyolefin compositions

ABSTRACT

Bis(substituted thioalkyl)hydroxylamine derivatives are effective in stabilizing polyolefin compositions containing a stabilizer or mixture of stabilizers selected from the group consisting of the phenolic antioxidants, the hindered amine light stabilizers, the alkylated hydroxybenzoate light stabilizers, the ultraviolet light absorbers, the organic phosphorus compounds, the alkaline metal salts of fatty acids and the thiosynergists, against degradation upon high temperature extrusion, exposure to the combustion products of natural gas, gamma irradiation or upon storage for extended periods.

BACKGROUND OF THE INVENTION

The present invention pertains to polyolefin compositions containing a stabilizer or mixture of stabilizers selected from the group consisting of the phenolic antioxidants, the hindered amine light stabilizers, the alkylated hydroxybenzoate light stabiizers, the ultraviolet light absorbers, the organic phosphorus compounds, the alkaline metal salts of fatty acids and the thiosynergists, which are stabilized against degradation and/or discoloration by an effective amount of a bis(substituted thioalkyl)hydroxylamine derivative.

The present invention also pertains to novel bis(hindered phenolic thioalkyl)hydroxylamines.

Although phenolic antioxidants have long been known to be very effective stabilizers for polyolefins and have enjoyed wide commercial success for that use, polyolefin compositions stabilized with phenolic antioxidants tend to discolor upon heating at elevated temperatures for prolonged periods or upon exposure to the combustion products of natural gas.

While the concomitant addition of organic phosphites to such polyolefin compositions mitigates the discoloration, it remains a serious practical problem.

Likewise polyolefin compositions containing certain phenolic antioxidants and hindered amine light stabilizers tend to discolor upon storage for extended periods even at ambient temperatures.

The organic hydroxylamine compounds, such as N,N-dibenzylhydroxylamine, are generally known and some are commercially available.

U.S. Pat. Nos. 3,644,278 and 3,778,464 describe the use of substituted hydroxylamines of varying structures as antioxidant stabilizers for hydrocarbons including polyolefins. The use of such substituted hydroxylamines in polyolefins in combination with a phenolic antioxidant or in combination with an organic phosphorus compound, an ultraviolet light absorber, a thiosynergist or a hindered amine light stabilizer with the resulting resistance to degradation and/or discoloration is not disclosed or suggested.

U.S. Pat. No. 3,408,422 discloses the use of selected hydroxylamine derivatives in unsaturated polyester compositions to prevent premature gelation on storage.

U.S. Pat. No. 3,926,909 describes the use of substituted hydroxylamines as stabilizers to prevent the discoloration of polyurethanes (Spandex) upon exposure to light, smog or gas fumes.

U.S. Pat. No. 4,242,224 discloses that the pink discoloration which occurs in the amine antioxidant and antiozonant emulsions used in the latex industry at high pH values can be prevented or retarded by the use of dialkylhydroxylamine or mercaptan stabilizers.

U.S. Pat. No. 4,316,996 pertains to a process of preparing phenolic antioxidants in the presence of a hydroxylamine derivative and of a substituted oxime to yield a phenolic antioxidant which itself exhibits improved color and color stability. It is stated that, when such antioxidants are incorporated into rubber, the amount and rate of discoloration is reduced. The instant compositions are not discolosed or suggested.

U.S. Pat. No. 3,432,578 relates to conjugated diene polymer compositions stabilized against the adverse effects of ultraviolet light by use of diaryl or diaralkyl hydroxylamine compounds including N,N-dibenzylhydroxylamine. It is noted that the dialkylhydroxylamines are completely ineffective in stabilizing such polymer compositions. This patent mentions that other stabilizers may be used in conjunction with the hydroxylamine derivative and in Table I discloses stabilized compositions consisting of a conjugated diene polymer, phenolic antioxidants and N,N-dibenzylhydroxylamine. Such compositions were resistant to decomposition upon ultraviolet exposure.

U.S. Pat. No. 4,386,224 discloses the use of N,N-diethylhydroxylamine as a color stabilizer for monoalkyl phenols such as nonyl or dodecyl phenol.

Some bis(substituted thioalkyl)hydroxylamines are known compounds per se. K. Ito et al, Chem. Pharm. Bull., 27, 1691 (1979) describes the Mannich-type condensation of selected mercaptans, formaldehyde and hydroxylamine to yield compounds derived from propyl mercaptan, amyl mercaptan, cyclohexyl mercaptan, benzyl mercaptan, thiophenol and ethylene dimercaptan. Related compounds derived from N-methylhydroxylamine, N-benzylhydroxylamine and N-phenylhydroxylamine are also described.

The possible use of such compounds as stabilizers for polyolefins or other substrates is not described or suggested by the authors who were interested in the possible pharmaceutical applications of said compounds. The hindered phenolic thioalkyl hydroxylamines derived from thiohydroquinone or benzyl mercaptan are not described or suggested.

G. Rawson et al, Tetrahedron, 26, 5653 (1970) describe the preparation of N,N-(di-p-tolylthiomethyl)hydroxylamine and of N,N'-(di-p-bromophenylthiomethyl)hydroxylamine in an academic study. No practical utility for said compounds is disclosed.

OBJECT OF THE INVENTION

A primary object of the instant invention is to provide novel bis(hindered phenolic thioalkyl)hydroxylamines which are effective stabilizers for polyolefins and other substrates subject to oxidative, thermal or light-induced degradation.

The broad object of the instant invention is to provide a polyolefin or other polymer composition, stabilized against degradation, which contains a stabilizer or mixture of stabilizers selected from the group consisting of the phenolic antioxidants, the hindered amine light stabilizers, the alkylated hydroxybenzoate light stabilizers, the ultraviolet light absorbers, the organic phosphorus compounds and the thiosynergists, which also contain a hydroxylamine derivative.

An object of the present invention is to provide a stabilized polyolefin composition containing a phenolic antioxidant which is stabilized against discoloration upon exposure to heating or to the combustion products of natural gas by the concomitant presence of a hydroxylamine derivative.

Still another object of the present invention is to provide a stabilized polyolefin composition containing an alkaline metal salt of a fatty acid or said metal salt and a phenolic antioxidant which is stabilized against discoloration upon exposure to heating or to the combustion products of natural gas by the concomitant presence of a hydroxylamine derivative.

DETAILED DISCLOSURE

The instant invention pertains to compounds of formula I ##STR1## wherein R₁ and R₂ are independently ##STR2## R₄ and R₅ are independently alkyl of 1 to 18 carbon atoms, cycloalkyl of 5 to 6 carbon atoms, phenyl, alkaryl of 7 to 18 carbon atoms or aralkyl of 7 to 9 carbon atoms, and R₃ is hydrogen or alkyl of 1 to 12 carbon atoms.

Preferably R₁ and R₂ are each the same; and preferably R₃ is hydrogen.

Preferably R₄ and R₅ are the same and are branched chain alkyl of 4 to 8 carbon atoms, most preferably tert-butyl.

When R₄ or R₅ is alkyl of 1 to 18 carbon atoms, R₄ or R₅ is for example methyl, ethyl, isopropyl, n-butyl, tert-butyl, tert-amyl, n-hexyl, tert-octyl, n-decyl, tert-dodecyl, hexadecyl or octadecyl.

R₄ or R₅ may also be cycloalkyl of 5 to 6 carbon atoms such as, for example, cyclopentyl or cyclohexyl.

R₄ or R₅ may also be aralkyl of 7 to 9 carbon atoms such as, for example, benzyl, alpha-methylbenzyl or alpha,alpha-dimethylbenzyl.

When R₄ or R₅ is alkaryl of 7 to 18 carbon atoms, R₄ or R₅ is for example, phenyl substituted by alkyl of 1 to 12 carbon atoms.

R₃ may be alkyl of 1 to 4 carbon atoms such as, for example, methyl, ethyl, n-propyl or n-butyl.

The compounds of formula I may be prepared by the Mannich reaction using the appropriate substituted thiohydroquinone or benzyl mercaptan, aldehyde and hydroxylamine hydrohalide.

These intermediates are largely items of commerce or can be prepared by known methods.

This invention also pertains to a composition stabilized against degradation which comprises

(a) a material subject to oxidative, thermal or light-induced degradation,

(b) a stabilizing amount of a compound of formula A ##STR3## wherein T₁ and T₂ are independently alkyl of 1 to 18 carbon atoms, cycloalkyl of 5 to 6 carbon atoms, phenyl, alkaryl of 7 to 18 carbon atoms, aralkyl of 7 to 9 carbon atoms or ##STR4## where T₄ and T₅ are independently alkyl of 1 to 18 carbon atoms, cycloalkyl of 5 to 6 carbon atoms, phenyl, alkaryl of 7 to 18 carbon atoms or aralkyl of 7 to 9 carbon atoms; or

T₁ and T₂ together are alkylene of 2 to 3 carbon atoms; and

T₃ is hydrogen or alkyl of 1 to 12 carbon atoms.

Preferably T₁ and T₂ are each the same, and preferably T₃ is hydrogen.

Preferably T₁ and T₂ are each the same and are alkyl of 12 to 18 carbon atoms or ##STR5## where T₄ and T₅ are each the same and are branched chain alkyl of 4 to 8 carbon atoms, most preferably tert-butyl.

The definitions of T₁ to T₅ largely correspond to those recited for R₁ to R₅ above. When T₁ or T₂ are alkyl of over 12 carbon atoms, T₁ or T₂ is, for example, n-tetradecyl, n-hexadecyl or n-octadecyl.

T₁ and T₂ together as alkylene of 2 to 3 carbon atoms are ethylene, trimethylene or propylene.

The compounds of formula A are prepared by the same general method as those of formula I using intermediates which are largely items of commerce.

The compounds of formula A where T₁ and T₂ are independently alkyl of 8 to 18 carbon atoms, and T₃ is hydrogen or alkyl of 1 to 12 carbon atoms are novel compounds.

The preferred compounds of formula A are those where T₁ and T₂ are each the same and are alkyl of 12 to 18 carbon atoms, and T₃ is hydrogen or alkyl of 1 to 4 carbon atoms.

The compounds of formula A are effective stabilizers in a wide range of organic substrates. Polymers which can be stabilized include:

1. Polymers which are derived from mono- or diolefins, e.g., polyethylene which can optionally be crosslinked, polypropylene, polyisobutylene, polymethylbutene-1, polymethylpentene-1, polyisoprene, polybutadiene.

2. Mixtures of the homopolymers cited under (1), for example mixtures of polypropylene and polyethylene, polypropylene and polybutene-1, polypropylene and polyisobutylene.

3. Copolymers of the monomers based on the homopolymers cited under (1), for example ethylene/propylene copolymers, propylene/butene-1 copolymers, propylene/isobutylene copolymers, ethylene/butene-1 copolymers as well as terpolymers of ethylene and propylene with a diene, for example hexadiene, dicyclopentadiene or ethylidene norbornene, and copolymers of α-olefins, e.g., ethylene with acrylic or methacrylic acid.

4. Polystyrene.

5. Copolymers of styrene and of α-methylstyrene, for example styrene/butadiene copolymers, styrene/acrylonitrile copolymers, styrene/acrylonitrile/methacrylate copolymers, styrene/acrylonitrile copolymers modified with acrylic ester polymers to provide impact strength as well as block copolymers, e.g., styrene/butadiene/styrene block copolymers.

6. Graft copolymers of styrene, for example the graft polymer of styrene to polybutadiene, the graft polymer of styrene with acrylonitrile to polybutadiene as well as mixtures thereof with the copolymers cited under (5), commonly referred to as acrylonitrile/butadiene/styrene or ABS plastics.

7. Halogen-containing vinyl polymers, for example polyvinyl chloride, polyvinylidene chloride, polyvinyl fluoride, polychloroprene, chlorinated rubbers, vinyl chloride/vinylidene chloride copolymers, vinyl chloride/vinyl acetate copolymers, vinylidene chloride/vinyl acetate copolymers.

8. Polymers which are derived from α,β-unsaturated acids and derivatives thereof, such as polyacrylates and polymethacrylates, polyacrylic amides and polyacrylonitrile.

9. Polymers which are derived from unsaturated alcohols and amines and from the acyl derivatives thereof or acetals, for example polyvinyl alcohol, polyvinyl acetate, polyvinyl stearate, polyvinyl benzoate, polyvinyl maleate, polyvinyl butyral, polyallyl phthalate, polyallyl melamine and copolymers thereof with other vinyl compounds, for example ethylene/vinyl acetate copolymers.

10. Homopolymers and copolymers which are derived from epoxides, for example polyethylene oxide or the polymers which are derived from bis-glycidyl ethers.

11. Polyacetals, for example polyoxymethylene, as well as polyoxymethylenes which contain ethylene oxide as comonomer.

12. Polyalkylene oxides, for example polyoxyethylene, polypropylene oxide or polybutylene oxide.

13. Polyphenylene oxides.

14. Polyurethanes and polyureas, such as in urethane coatings.

15 Polycarbonates.

16. Polysulfones.

17. Polyamides and copolyamides which are derived from diamines and dicarboxylic acids and/or from aminocarboxylic acids or the corresponding lactams, for example polyamide 6, polyamide 6/6, polyamide 6/10, polyamide 11, polyamide 12, poly-m-phenylene-isophthalamide.

18. Polyesters which are derived from dicarboxylic acids and dialcohols and/or from hydroxycarboxylic acids or the corresponding lactones, for example polyethylene glycol terephthalate, poly-1,4-dimethylol-cyclohexane terephthalate.

19. Cross-linked polymers which are derived from aldehydes on the one hand and from phenols, ureas and melamine on the other, for example phenol/formaldehyde, urea/formaldehyde and melamine/formaldehyde resins.

20. Alkyl resins, for example glycerol/phthalic acid resins and mixtures thereof with melamine/formaldehyde resins.

21. Unsaturated polyesters resins which are derived from copolyesters of saturated and unsaturated dicarboxylic acids with polyhydric alcohols as well as from vinyl compounds as cross-linking agents and also the halogen-containing, flame-resistant modifications thereof.

22. Natural polymers, for example cellulose, rubber, as well as the chemically modified homologous derivatives thereof, for example cellulose acetates, cellulose propionates and cellulose butyrates and the cellulose ethers, for example methyl cellulose.

The stabilizing of polyolefins, styrene polymers and polyamides and of polyurethanes is of particular importance, and the instant copolymers are outstandingly suitable for this. Examples of such polymers are high density and low density polyethylene, polypropylene, ethylene/propylene copolymers, polystyrene, styrene/butadiene/acrylonitrile terpolymers, mixtures of polyolefins or of styrene polymers, and polyurethanes based on polyethers or polyesters, in the form of lacquers, filaments, films, sheets, elastomers or foams.

The instant compounds of formula A are particularly effective in stabilizing material subject to oxidative, thermal or light-induced degradation where said material is selected from the group consisting of acrylonitrile-butadiene-styrene (ABS) resins, impact polystyrene, poly(phenylene oxide), polybutadiene, polyisoprene, natural rubber and lubricating oils.

The instant stabilizers are added to the plastics or oil in a concentration of 0.05 to 5% by weight, calculated relative to the material to be stabilized. Preferably, 0.1 to 2.5% by weight of the stabilizer calculated relative to the material to be stabilized, is incorporated into the latter.

Incorporation can be effected after polymerization, for example by mixing the compounds and, if desired, further additives into the melt by the methods customary in the art, before or during shaping, or by applying the dissolved or dispersed compounds to the polymer, with subsequent evaporation of the solvent if necessary.

The stabilizers can also be added to the plastics to be stabilized in the form of a master batch which contains these compounds, for example in a concentration of 2.5 to 25% by weight.

Although the compounds of the invention may be used to provide a light stabilizing function, the compounds of this invention are often combined with other stabilizers, even other light stabilizers, in the preparation of stabilized compositions. The stabilizers may be used with phenolic antioxidants, pigments, colorants or dyes, light stabilizers such as hindered amines, metal deactivators, etc.

In general, the stabilizers of this invention are employed from about 0.05 to about 5% by weight of the stabilized composition, although this will vary with the particular substrate and application. An advantageous range is from about 0.1 to about 2.5%.

The stabilizers of formula A may readily be incorporated into the organic polymers by conventional techniques, at any convenient stage prior to the manufacture of shaped articles therefrom. For example, the stabilizer may be mixed with the polymer in dry powder form, or a suspension or emulsion of the stabilizer may be mixed with a solution, suspension, or emulsion of the polymer. The stabilized polymer compositions of the invention may optionally also contain from about 0.05 to about 5%, preferably from about 0.1 to about 2.5% by weight of various conventional additives, such as the following, particularly phenolic antioxidants or light-stabilizers, or mixtures thereof:

1. Antioxidants

1.1 Simple 2,6-dialkylphenols, such as, for example, 2,6-di-tert.-butyl-4-methylphenol, 2-tert.-butyl-4,6-dimethylphenol, 2,6-di-tert.-butyl-4-methoxymethylphenol and 2,6-dioctadecyl-4-methylphenol.

1.2 Derivatives of alkylated hydroquinones, such as for example, 2,5-di-tert.-butyl-hydroquinone, 2,5-di-tert.-amylhydroquinone, 2,6-di-tert.-butyl-hydroquinone, 2,5-di-tert.-butyl-4-hydroxy-anisole, 3,5-di-tert.-butyl-4-hydroxy-anisole, 3,5-di-tert.-butyl-4-hydroxyphenyl stearate and bis-(3,5-di-tert.-butyl-4-hydroxyphenyl)adipate.

1.3 Hydroxylated thiodiphenyl ethers, such as for example, 2,2'-thio-bis-(6-tert.-butyl-4-methylphenol), 2,2'-thio-bis-(4-octylphenol), 4,4'-thio-bis-(tert.-butyl-3-methylphenol), 4,4'-thio-bis-(3,6-di-sec.-amylphenol), 4,4'-thio-bis-(6-tert.-butyl-2-methylphenol) and 4,4'-bis-(2,6-dimethyl-4-hydroxyphenyl)disulfide.

1.4 Alkylidene-bisphenols, such as, for example, 2,2'-methylene-bis-(6-tert.-butyl-4-methylphenol), 2,2'-methylene-bis-(6-tert.-butyl-4-ethylphenol), 4,4'-methylene-bis-(6-tert.-butyl-2-methylphenol), 4,4'-methylene-bis-(2,6-di-tert.-butylphenol), 2,6-di-(3-tert.-butyl-5-methyl-2-hydroxybenzyl)-4-methylphenol, 2,2'-methylene-bis-[4-methyl-6-(-methylcyclohexyl)-phenol], 1,1-bis(3,5-dimethyl-2-hydroxyphenyl)-butane, 1,1-bis-(5-tert.-butyl-4-hydroxy-2-methylphenyl)-butane, 2,2-bis-(3,5-di-tert.-butyl-4-hydroxyphenyl)-propane, 1,1,3-tris-(5-tert.-butyl-4-hydroxy-2-methylphenyl)-butane, 2,2-bis-(5-tert.-butyl-4-hydroxy-2-methylphenyl)-4-n-dodecylmercapto-butane, 1,1,5,5-tetra-(5-tert.-butyl-4-hydroxy-2-methylphenyl)-pentane and ethylene glycol bis-[3,3-bis-(3-tert.-butyl-4-hydroxyphenyl)-butyrate].

1.5 O-, N- and S-benzyl compounds, such as for example, 3,5,3',5'-tetra-tert.-butyl-4,4'-dihydroxydibenzyl ether, octadecyl 4-hydroxy-3,5-dimethylbenzyl-mercaptoacetate, tris-(3,5-di-tert.-butyl-4-hydroxybenzyl)-amine and bis-(4-tert.-butyl-3-hydroxy-2,6-dimethylbenzyl)dithioterephthalate.

1.6 Hydroxybenzylated malonates, such as for example, dioctadecyl 2,2-bis-(3,5-di-tert.-butyl-2-hydroxybenzyl)-malonate, dioctadecyl 2-(3-tert.-butyl-4-hydroxy-5-methylbenzyl)malonate, di-dodecylmercapto-ethyl 2,2-bis-(3,5-di-tert.-butyl-4-hydroxybenzyl)-malonate and di-[4-(1,1,3,3-tetramethylbutyl)phenyl] 2,2-bis-(3,5-di-tert.-butyl-4-hydroxybenzyl)-malonate.

1.7 Hydroxybenzyl-aromatic compounds, such as, for example, 1,3,5-tri-(3,5-di-tert.-butyl-4-hydroxybenzyl)-2,4,6-trimethyl-benzene, 1,4-di-(3,5-di-tert-butyl-4-hydroxybenzyl)-2,3,5,6-tetramethylbenzene and 2,4,6-tri-(3,5-di-tert.-butyl-4-hydroxy-benzyl)-phenol.

1.8 s-Triazine compounds, such as, for example 2,4-bis-octylmercapto-6-(3,5-di-tert.-butyl-4-hydroxy-anilino)-s-triazine, 2-octylmercapto-4,6-bis-(3,5-di-tert.-butyl-4-hydroxyanilino)-s-triazine, 2-octylmercapto-4,6-bis-(3,5-di-tert.-butyl-4-hydroxyphenoxy)-s-triazine, 2,4,6-tris-(3,5-di-tert.-butyl-4-hydroxyphenoxy)-s-triazine, 2,4,6-tris-(3,5-di-tert.-butyl-4-hydroxyphenylethyl)-s-triazine and 1,3,5-tris-(3,5-di-tert.-butyl-4-hydroxybenzyl)isocyanurate.

1.9 Amides of β-(3,5-di-tert.-butyl-4-hydroxyphenyl)-propionic acids, such as, for example 1,3,5-tris-(3,5,-di-tert.-butyl-4-hydroxyphenyl-propionyl)-hexahydro-s-triazine and N,N'-di-(3,5-di-tert.-butyl-4-hydroxyphenyl-propionyl)-hexamethylenediamine, N,N'-bis-β-(3,5-di-t-butyl-4-hydroxyphenyl)propionyl-hydrazine.

1.10 Esters of β-(3,5-di-tert.-butyl-4-hydroxyphenyl)-propionic acid with monohydric or polyhydric alcohols, such as for example, with methanol, ethanol, octadecanol, 1,6-hexanediol;. 1,9-nonanediol, ethylene glycol, 1,2-propane-diol, diethylene glycol, thiodietylene glycol, neopentylglycol, pentaerythritol, 3-thiaundecanol, 3-thia-pentadecanol, trimethylhexanediol, trimethylolethane, trimethylolpropane, tris-hydroxyethyl isocyanurate and 4-hydroxymethyl-1-phospha-2,6,7-trioxabicyclo-[2.2.2.]octane.

1.11 Esters of β-(5-tert.-butyl-4-hydroxy-3-methylphenyl)propionic acid with monohydric or polyhydric alcohols, such as for example, with methanol, ethanol, octadecanol, 1,6-hexanediol, 1-9-nonanediol, ethylene glycol, 1,2-propanediol, di-ethylene glycol, thiodiethylene glycol, neopentylglycol, pentaerythritol, 3-thia-undecanol, 3-thia-pentadecanol, trimethylhexanediol, trimethylolethane, trimethylolpropane, tris-hydroxyethyl isocyanurate and 4-hydroxymethyl-1-phospha-2,6,7-trioxabicyclo[2.2.2.]octane.

1.12 Esters of 3,5-di-tert.-butyl-4-hydroxyphenylacetic acid with monohydric or polyhydric alcohols, such as for example, with methanol, ethanol, octadecanol, 1,6-hexandiol, 1,9-nonanediol, ethylene glycol, 1,2-propenediol, diethylene glycol, thiodiethylene glycol, neopentylglycol, pentaerythritol, 3-thia-undecanol, 3-thia-pentadecanol, trimethylhexanediol, trimethylolethane, trimethylolpropane, tris-hydroxyethyl isocyanurate and 4-hydroxymethyl-1-phospha-2,6,7-trioxabicyclo[2.2.2]-octane, especially the tetrakis ester of pentaerythritol.

1.13 Benzylphosphonates, such as, for example, dimethyl 3,5-di-tert.-butyl-4-hydroxybenzylphosphonate, diethyl 3,5-di-tert.-butyl-4-hydroxybenzylphosphonate, dioctadecyl 3,5-di-tert.-butyl-4-hydroxybenzylphosphonate and dioctadecyl 5-tert.-butyl-4-hydroxy-3-methylbenzylphosphonate.

2. Light-stabilizers

2.1 Esters of optionally substituted benzoic acids, e.g., 3,5-di-tert.-butyl-4-hydroxybenzoic acid, 2,4-di-tert.-butylphenyl ester or -octadecyl ester or 2-methyl-4,6-di-tert.-butylphenyl ester.

2.2 Sterically hindered amines e.g., 4-benzoyl-2,2,6,6-tetramethylpiperidine, 4-stearyloxy-2,2,6,6-tetramethyl-piperidine, bis-(2,2,6,6-tetramethylpiperidyl)sebacate, bis-(1,2,2,6,6-pentamethylpiperidyl)sebacate, bis-(1,2,2,6,6-pentamethylpiperidyl)-2-n-butyl-2-(2-hydroxy-3,5-di-tert-butylbenzyl)malonate or 3-n-octyl-7,7,9,9-tetra-methyl-1,3,8-triazaspiro[4.5]decane-2,4-dione.

2.3 Oxalic acid diamides, e.g., 4,4'-di-octyloxy-oxanilide, 2,2'-di-octyloxy-5,5'-di-tert.butyl-oxanilide, 2,2'-didodecycloxy-5,5'-di-tert.-butyl-oxanilide, 2-ethoxy-2'-ethyl-oxanilide, N,N'-bis-(3-dimethyl-aminopropyl)-oxalamide, 2-ethoxy-5-tert.-butyl-2'-ethyl-oxanilide and the mixture thereof with 2-ethoxy-2'-ethyl-5,4'-di-tert.-butyl-oxanilide, or mixture of ortho- and para-methoxy- as well as of o- and p-ethoxy-disubstituted oxanilides.

3. Metal deactivators, e.g., oxanilide, isophthalic acid dihydrazide, sebacic acid-bis-phenylhydrazide, bis-benzylidene-oxalic acid dihydrazide, N,N'-diacetal-adipic acid dihydrazide, N,N'-bis-salicyloyl-oxalic acid dihydrazide, N,N'-bis-salicyloylhydrazine, N,N'-bis-(3,5-di-tert.-butyl-4-hydroxyphenylpropionyl)-hydrazine, N-salicyloyl-N'-salicylalhydrazine, 3-salicyloyl-amino-1,2,4-triazole or N,N'-bis-salicyloyl-thiopropionic acid dihydrazide.

4. Basic co-stabilizers, e.g. alkali metal salts and alkaline-earth metal salts of higher fatty acids, for example Ca-stearate, Zn-stearate, Mg-behenate, Na-ricinoleate or K-palmitate.

5. Nucleation agents, e.g., 4-tert.-butylbenzoic acid, adipic acid or diphenylacetic acid.

6. Phosphites and phosphonites, such as, for example, triphenyl phosphite, diphenylalkyl phosphites, phenyldialkyl phosphites, tri-(nonyl-phenyl)phosphite, trilauryl phosphite, trioctadecyl phosphite and 3,9-isodecyloxy-2,4,8,10-tetraoxa-3,9-diphospha-[5.5]-undecane and tetra(2,4-di-tert-butylphenyl)diphenylene-4,4'-bis(phosponite).

Other additives that can be incorporated in the stabilized compositions are thiosynergists, such as dilauryl thiodiproprionate, lubricants such as stearyl alcohol, fillers, asbestos, kaolin, talc, glass fibers, pigments, optical brighteners, flameproofing agents and antistatic agents.

This invention also pertains to a composition, stabilized against degradation, which comprises

(a) a saturated polyolefin or mixture thereof,

(b) a stabilizing amount of a stabilizer or mixture of stabilizers selected from the group consisting of the phenolic antioxidants, the hindered amine light stabilizers, the alkylated hydroxybenzoate light stabilizers, the ultraviolet light absorbers, the organic phosphorus compounds, the alkaline metal salts of fatty acids and the thiosynergists, and

(c) a stabilizing amount of a hydroxylamine, or mixture of said hydroxylamines, of formula A.

The instant composition is stabilized against degradation and/or discoloration upon exposure to heating at elevated temperatures, to the combustion products of natural gas, to gamma irradiation or to prolonged storage at ambient temperature.

More particularly, the instant invention pertains to a stabilized composition wherein component (b) is a stabilizing amount of a phenolic antioxidant or mixture thereof in combination with a stabilizing amount of an alkaline metal salt of a fatty acid or mixture thereof.

The saturated polyolefins useful in the instant compositions are the polymers, derived from monoolefins, such as polyethylene, which can optionally be crosslinked, polypropylene, polyisobutylene, polybutene-1, poly-3-methylbutene-1 and polymethylpentene-1. Polyethylene may be for example medium density, high density or linear low density polyethylene.

Mixtures of the homopolymers cited above, for example mixtures of polypropylene and polyethylene, polypropylene and polybutene-1, or polypropylene and polyisobutylene and the like, may also be used.

Copolymers of monoolefins may also be used in the instant compositions, for example ethylene/propylene copolymers, propylene/butene-1 copolymers, propylene/octene-1 copolymers, ethylene/butene-1 copolymers, ethylene/octene-1 copolymers as well as ethylene/vinyl acetate copolymers.

The instant compositions particularly employ as the polyolefin component polyethylene, polypropylene, polyisobutylene, poly(butene-1), poly(pentene-1), poly(3-methylbutene-1), poly(4-methyl-pentene-1) and various ethylene or propylene copolymers.

Especially preferred polyolefin substrates are polypropylene, low density polyethylene, medium density polyethylene, high density polyethylene, linear low density polyethylene, poly(butene-1), ethylene/vinyl acetate copolymer, ethylene/propylene copolymer and copolymers of ethylene or of propylene with other alpha olefins.

The most preferred polyolefin substrate is polypropylene, high density polyethylene, ethylene/propylene copolymer or a copolymer of ethylene or of propylene with another alpha olefin.

The phenolic antioxidants useful in the instant compositions embrace a large family of compounds examples of which are given below.

Antioxidants:

Simple 2,6-dialkylphenol, such as, for example, 2,6-di-tert.-butyl-4-methylphenol, 2-tert.-butyl-4,6-dimethylphenol, 2,6-di-tert.-butyl-4-methoxymethylphenol 2,6-dioctadecyl-4-methylphenol and 2,6-di-tert-butylphenol.

Derivatives of alkylated hydroquinones, such as for example, 2,5-di-tert.-butyl-hydroquinone, 2,5-di-tert.-amylhydroquinone, 2,6-di-tert.-butyl-hydroquinone, 2,5-di-tert.-butyl-4-hydroxy-anisole, 3,5-di-tert.-butyl-4-hydroxy-anisole, tris-(3,5-di-tert.-butyl-4-hydroxyphenyl)phosphite, 3,5-di-tert.-butyl-4-hydroxyphenyl stearate and bis-(3,5-di-tert.-butyl-4-hydroxyphenyl)adipate.

Hydroxylated thiodiphenyl ethers, such as, for example, 2,2'-thio-bis-(6-tert.-butyl-4-methylphenol), 2,2'-thio-bis-(4-octylphenol), 4,4'-thio-bis-(6-tert.-butyl-3-methylphenol), 4,4'-thio-bis-(3,6-di-sec.-amylphenol), 4,4'-thio-bis-(6-tert.-butyl-2-methylphenol) and 4,4'-bis-(2,6-dimethyl-4-hydroxyphenyl)disulfide.

Alkylidene-bisphenols, such as, for example, 2,2'-methylene-bis-(6-tert.-butyl-4-methylphenol), 2,2'-methylene-bis-(6-tert.-butyl-4-ethylphenol), 4,4'-methylene-bis-(6-tert.-butyl-2-methylphenol), 4,4'-methylene-bis-(2,6-di-tert.-butylphenol), 2,6-di(3,-tert.-butyl-5-methyl-2-hydroxybenzyl)-4-methylphenol, 2,2'-methylene-bis-[4-methyl-6-(α-methylcyclohexyl)-phenol], 1,1-bis(3,5-dimethyl-2-hydroxyphenyl)-butane, 1,1-bis-(5-tert.-butyl-4-hydroxy-2-methylphenyl)-butane, 2,2-bis-(3,5-di-tert.-butyl-4-hydroxyphenyl)-propane, 1,1,3-tris-(5-tert.-butyl-4-hydroxy-2-methylphenyl)-butane, 2,2-bis-(5-tert.-butyl-4-hydroxy-2-methylphenyl)-4-n-dodecylmercaptobutane, 1,1,5,5-tetra-(5-tert.-butyl-4-hydroxy-2-methylphenyl)pentane and ethylene glycol bis-[3,3-bis-(3-tert.-butyl-4-hydroxyphenyl)-butyrate].

O-, N- and S-benzyl compounds, such as, for example, 3,5,3',5'-tetra-tert.-butyl-4,4'-dihydroxydibenzyl ether, octadecyl 4-hydroxy-3,5-dimethylbenzyl-mercaptoacetate, tris-(3,5-di-tert.-butyl-4-hydroxybenzyl)-amine and bis-(4-tert.-butyl-3-hydroxy-2,6-dimethylbenzyl)dithioterephthalate.

Hydroxybenzylated malonates, such as for example, dioctadecyl 2,2-bis-(3,5-di-tert.-butyl-2-hydroxybenzyl)-malonate, dioctadecyl 2-(3-tert.-butyl-4-hydroxy-5-methylbenzyl)-malonate, di-dodecylmercapto-ethyl 2,2-bis-(3,5-di-tert.-butyl-4-hydroxybenzyl)-malonate and di-[4-(1,1,3,3-tetramethylbutyl)phenyl] 2,2-bis-(3,5-di-tert.-butyl-4-hydroxybenzyl)-malonate.

Hydroxybenzyl-aromatic compounds, such as, for example, 1,3,5-tri-(3,5-di-tert.-butyl-4-hydroxybenzyl)-2,4,6-trimethylbenzene, 1,4-di-(3,5-di-tert-butyl-4-hydroxybenzyl)-2,3,5,6-tetramethylbenzene and 2,4,6-tri(3,5-di-tert.-butyl-4-hydroxybenzyl)-phenol.

s-Triazine compounds, such as, for example, 2,4-bisoctylmercapto-6-(3,5-di-tert.-butyl-4-hydroxy-anilino)-s-triazine, 2-octylmercapto, 4,6-bis-(3,5-di-tert.-butyl-4-hydroxy anilino)-s-triazine, 2-octylmercapto-4,6-bis-(3,5-di-tert.-butyl-4-hydroxyphenoxy)-s-triazine, 2,4,6-tris-(3,5-di-tert.-butyl-4-hydroxyphenoxy)-s-triazine, 2,4,6-tris-(3,5-di-tertbutyl-4-hydroxyphenylethyl)-s-triazine, 1,3,5-tris-(2,6-dimethyl-3-hydroxy-4-tert-butylbenzyl)isocyanurate and 1,3,5-tris-(3,5-di-tert.-butyl-4-hydroxybenzyl)isocyanurate.

Amides of β-(3,5-di-tert.-butyl-4-hydroxyphenyl)-propionic acid, such as, for example, 1,3,5-tris-(3,5-di-tert.-butyl-4-hydroxyphenyl-propionyl)-hexahydro-s-triazine and N,N'-di (3,5-di-tert.-butyl-4-hydroxyphenyl-propionyl)-hexamethylenediamine. N,N'-bis-β-(3,5-di-t-butyl-4-hydroxyphenyl)-propionylhydrazine.

Esters of β-(3,5-di-tert.-butyl-4-hydroxyphenyl)-propionic acid with monohydric or polyhydric alcohols, such as, for example, with methanol, ethanol, octadecanol, 1,6-hexanediol, 1,9-nonanediol, ethylene glycol, 1,2-propanediol, diethylene glycol, thiodiethylene glycol, triethylene glycol, neopentylglycol, pentaerythritol, 3-thia-undecanol, 3-thia-pentadecanol, trimethylhexanediol, trimethylolethane, trimethylolpropane, tris-hydroxyethyl isocyanurate and 4-hydroxymethyl-1-phospha-2,6,7-trioxabicyclo-[2.2.2.]octane.

Esters of β-(5-tert.-butyl-4-hydroxy-3-methylphenyl)-propionic acid with monohydric or polyhydric alcohols, such as, for example, with methanol, ethanol, octadecanol, 1,6-hexanediol, 1,9-nonanediol, ethylene glycol, 1,2-propanediol, diethylene glycol, triethylene glycol, thiodiethylene glycol, neopentylglycol, pentaerythritol, 3-thia-undecanol, 3-thia-pentadecanol, trimethylhexanediol, trimethylolethane, trimethylolpropane, tris-hydroxyethyl isocyanurate and 4-hydroxymethyl-1-phospha-2,6,7-trioxabicyclo[2.2.2]octane.

Esters of 3,5-di-tert.-butyl-4-hydroxyphenylacetic acid with monohydric or polyhydric alcohols, such as for example, with methanol, ethanol, octadecanol, 1,6-hexandiol, 1,9-nonanediol, ethylene glycol, 1,2-propenediol, diethylene glycol, thio-diethylene glycol, neopentylglycol, pentaerythritol, 3-thia-undecanol, 3-thia-pentadecanol, trimethylhexanediol, trimethylolethane, trimethylolpropane, tris-hydroxyethyl isocyanurate and 4-hydroxymethyl-1-phospha-2,6,7-trioxabicyclo[2.2.2]octane, especially the tetrakis ester of pentaerythritol.

Benzylphosphonates, such as, for example, dimethyl 3,5-di-tert.-butyl-4-hydroxybenzylphosphonate, diethyl 3,5-di-tert.-butyl-4-hydroxybenzylphosphonate, dioctadecyl 3,5-di-tert.-butyl-4-hydroxybenzylphosphonate and dioctadecyl 5-tert.-butyl-4-hydroxy-3-methylbenzylphosphonate.

The phenolic antioxidant of particular interest is selected from the group consisting of n-octadecyl 3,5-di-tert-butyl-4-hydroxyhydrocinnamate, neopentanetetrayl tetrakis(3,5-di-tert-butyl-4-hydroxyhydrocinnamate), di-n-octadecyl 3,5-di-tert-butyl-4-hydroxybenzylphosphonate, 1,3,5-tris(3,5-di-tert-butyl-4-hydroxybenzyl)isocyanurate, thiodiethylene bis(3,5-di-tert-butyl-4-hydroxyhydrocinnamate), 1,3,5-trimethyl-2,4,6-tris(3,5-di-tert-butyl-4-hydroxybenzyl)benzene, 3,6-dioxaoctamethylene bis(3-methyl-5-tert-butyl-4-hydroxyhydrocinnamate), 2,6-di-tert-butyl-p-cresol, 2,2'-ethylidene-bis(4,6-di-tert-butylphenol), 1,3,5-tris(2,6-dimethyl4-tert-butyl-3-hydroxybenzyl)isocyanurate, 1,1,3-tris(2-methyl-4-hydroxy-5-tert-butylphenyl)butane, 1,3,5-tris[2-(3,5-di-tert-butyl-4-hydroxyhydrocinnamoyloxy)ethyl]isocyanurate, 3,5-di-(3,5-di-tert-butyl-4-hydroxybenzyl)mesitol, hexamethylene bis(3,5-di-tert-butyl-4-hydroxyhydrocinnamate), 1-(3,5-di-tert-butyl-4-hydroxyanilino)-3,5-di(octyl-thio)-s-triazine, N,N'-hexamethylene-bis(3,5-di-tert-butyl-4-hydroxyhydrocinnamamide), calcium bis(ethyl 3,5-di-tert-butyl-4-hydroxybenzylphosphonate), ethylene bis[3,3-di(3-tert-butyl-4-hydroxyphenyl)butyrate], octyl 3,5-di-tert-butyl-4-hydroxybenzylmercaptoacetate, bis(3,5-tert-butyl-4-hydroxyhydrocinnamoyl)hydrazide, and N,N'-bis-[2-(3,5-di-tert-butyl-4-hydroxyhydrocinnamoyloxy)ethyl]oxamide.

A most preferred embodiment has as the phenolic antioxidant, neopentanetetrayl tetrakis(3,5-di-tert-butyl-4-hydroxyhydrocinnamate), n-octadecyl 3,5-di-tert-butyl-4-hydroxyhydrocinnamate, 1,3,5-trimethyl-2,4,6-tris(3,5-di-tert-butyl-4-hydroxybenzyl)benzene, 1,3,5-tris(3,5-di-tert-butyl-4-hydroxybenzyl)isocyanurate, 2,6-di-tert-butyl-p-cresol or 2,2'-ethylidene-bis(4,6-di-tert-butyl-phenol).

When the instant compositions contain an alkaline metal salt of a fatty acid, such salts are the alkali metal, alkaline earth metal, zinc, cadmium or aluminum salts of the higher fatty acids for example calcium stearate, zinc stearate, magnesium behenate, sodium ricinoleate or potassium palmitate. Calcium stearate is particularly preferred.

When the instant compositions contain an organic phosphorus compound, such compounds may be for example, triphenyl phosphite, diphenylalkyl phosphites, phenyldialkyl phosphites, tri-(nonylphenyl) phosphite, trilauryl phosphite, trioctadecyl phosphite, di(isodecyloxy-2,4,8,10-tetraoxa-3,9-diphospha-[5.5]-undecane and tri-(4-hydroxy-3,5-di-tert-butylphenyl)phosphite or similar phosphonites.

The organic phosphorus compound of particular interest is selected from the group consisting of tris(2,4-di-tert-butylphenyl)phosphite, 3,9-di(2,4-di-tert-butylphenoxy)-2,4,8,10-tetraoxa-3,9-diphospha[5.5]undecane, tris(p-nonylphenyl)phosphite, 3,9-distearyloxy-2,4,8,10-tetraoxa-3,9-diphospha[5.5]undecane, dilauryl phosphite, 3,9-di[2,6-di-tert-butyl-4-(2-(n-octadecyloxycarbonyl)ethyl)-phenoxy]-2,4,8,10-tetraoxa-3,9-diphospha[5.5]undecane and tetrakis(2,4-di-tert-butylphenyl) 4,4'-bis(diphenylene)phosphonite. Tris(2,4-di-tert-butylphenyl)phosphite is especially preferred.

When the instant compositions contain a thiosynergist, such thiosynergists may be for example dilauryl thiodiproionate, distearyl thiodipropionate or neopentanetetrayl tetrakis(3-dodecylthiopropionate). Distearyl thiodipropionate or dilauryl thiodipropionate is particularly preferred.

When the instant compositions contain a hindered amine light stabilizer, such hindered amines may for example be 4-benzoyl-2,2,6,6-tetramethylpiperidine, 4-stearyloxy-2,2,6,6-tetramethylpiperidine, bis-(2,2,6,6-tetramethylpiperidyl)sebacate or 3-n-octyl-7,7,9,9-tetramethyl-1,3,8-triaza-spiro[4.5]decane-2,4-dione.

The hindered amine light stabilizer of particular interest is selected from the group consisting of bis(2,2,6,6-tetramethylpiperidin-4-yl)sebacate, bis(1,2,2,6,6-pentamethylpiperidin-4-yl)sebacate, di(1,2,2,6,6-pentamethylpiperidin-4-yl) (3,5-di-tert-butyl-4-hydroxybenzyl)butylmalonate, tris(2,2,6,6-tetramethylpiperidin-4-yl)nitrilotriacetate, 1,2-bis(2,2,6,6-tetramethyl-3-oxopiperazin-4-yl)ethane, 2,2,4,4-tetramethyl-7-oxa-3,20-diaza-21-oxodispiro[5.1.11.2]heneicosane, polycondensation product of 2,4-dichloro-6-tert-octylamino-s-triazine and 4,4'-hexamethylenebis(amino-2,2,6,6-tetramethylpiperidine), polycondensation product of 1-(2-hydroxyethyl)-2,2,6,6-tetramethyl-4-hydroxypiperidine and succinic acid, polycondensation product of 4,4'-hexamethylenebis(amino-2,2,6,6-tetramethylpiperidine) and 1,2-dibromoethane, polycondensation product of 2,4-dichloro-6-morpholino-s-triazine and 4,4'-hexamethylenebis(amino-2,2,6,6-tetramethylpiperidine), N,N'N",N"'-tetrakis[(4,6-bis(butyl-(2,2,6,6-tetramethylpiperidin-4-yl)-amino-s-triazin-2-yl)-1,10-diamino-4,7-diazadecane, octamethylene bis(2,2,6,6-tetramethylpiperidin-4-carboxylate) and 4,4'-ethylenebis(2,2,6,6-tetramethylpiperazin-3-one).

A most preferred embodiment has as the hindered amine light stabilizer bis(2,2,6,6-tetramethylpiperidin-4-yl)sebacate, the polycondensation product of 1-(2-hydroxyethyl)-2,2,6,6-tetramethyl-4-hydroxypiperidine and succinic acid, the polycondensation product of 2,4-dichloro-6-tert-octylamino-s-triazine and 4,4'-hexamethylenebis(amino-2,2,6,6-tetramethylpiperidine) or N,N',N",N"'-tetrakis[(4,6-bis(butyl-(2,2,6,6-tetramethyl-piperidin-4-yl)amino)-s-triazine-2-yl]-1,10-diamino-4,7-diazadecane.

When the instant compositions contain an ultraviolet light absorber, such light absorbers may include the 2H-benzotriazoles, the benzophenones, the oxanilides, the alpha-cyanocinnamates the substituted benzoate esters or the nickel salts of the O-alkyl hindered phenolic benzylphosphonates.

Examples of such ultraviolet light absorbers are seen below.

UV-Absorbers

2-(2'-Hydroxyphenyl)-benzotriazoles, e.g., the 5'-methyl-, 3',5'-di-tert.-butyl-, 5'-tert.-butyl-, 5'-(1,1,3,3-tetramethylbutyl)-, 5-chloro-3',5'-di-tert.-butyl-, 5-chloro-3'-tert.-butyl-5'-methyl-, 3'-sec.-butyl-5'-tert.-butyl-, 3'-α-methylbenzyl-5'-methyl, 3'-α-methylbenzyl-5'-methyl-5-chloro-, 4'-hydroxy-, 4'-methoxy-,4'-octoxy-, 3',5'-di-tert.-amyl-, 3'-methyl-5'-carbomethoxyethyl- and 5-chloro-3',5'-di-tert.-amyl-derivative.

2,4-bis-(2'-Hydroxyphenyl)-6-alkyl-s-triazines, e.g., the 6-ethyl-, 6-heptadecyl- or 6-undecyl-derivative.

2-Hydroxybenzophenones e.g., the 4-hydroxy-, 4-methoxy-, 4-octoxy-, 4-decyloxy-, 4-dodecyloxy-, 4-benzyloxy-, 4,2',4'-trihydroxy-, 2,2',4,4'-tetrahydroxy- or 2'-hydroxy-4,4'-dimethoxy-derivative.

1,3-bis-(2'-Hydroxybenzoyl)-benzenes, e.g., 1,3-bis-(2'-hydroxy-4'-hexyloxy-benzoyl)-benzene, 1,3-bis-(2'-hydroxy-4'-octyloxy-benzoyl)-benzene or 1,3-bis-(2'-hydroxy-4'-dodecyloxybenzoyl)-benzene.

Esters of optionally substituted benzoic acids, e.g., phenylsalicylate, octylphenylsalicylate, dibenzoylresorcin, bis-(4-tert.-butylbenzoyl)-resorcin, benzoylresorcin, 3,5-di-tert.-butyl-4-hydroxybenzoic acid-2,4-di-tert.-butylphenyl ester or -octadecyl ester or -2-methyl-4,6-di-tert.-butyl ester.

Acrylates, e.g., α-cyano-β,β-diphenylacrylic acid-ethyl ester or isooctyl ester, α-carbomethoxy-cinnamic acid methyl ester, α-cyano-β-methyl-p-methoxy-cinnamic acid methyl ester or -butyl ester or N(β-carbomethoxyvinyl)-2-methyl-indoline.

Oxalic acid diamides, e.g., 4,4'-di-octyloxy-oxanilide, 2,2'-di-octyloxy-5,5'-di-tert.-butyl-oxanilide, 2,2'-di-dodecyloxy-5,5'-di-tert.-butyl-oxanilide, 2-ethoxy-2'-ethyl-oxanilide, N,N'-bis(3-dimethyl-aminopropyl)-oxalamide, 2-ethoxy-5-tert.-butyl-2'-ethyloxanilide and the mixture thereof with 2-ethoxy-2'-ethyl-5,4'-di-tert.-butyl-oxanilide, or mixtures of ortho- and para-methoxy- as well as of o- and p-ethoxy-disubstituted oxanilides.

Preferably the ultraviolet light absorber used in the instant compositions is 2-(2-hydroxy-5-methylphenyl)-2H-benzotriazole, 2-(2-hydroxy-3,5-di-tert-amylphenyl)-2H-benzotriazole, 2-[2-hydroxy-3,5-di-(alpha,alpha-dimethylbenzyl)phenyl]-2H-benzotriazole, 2-(2-hydroxy-5-tert-octylphenyl)-2H-benzotriazole, 2-hydroxy-4-octyloxybenzophenone, nickel bis(O-ethyl 3,5-di-tert-butyl-4-hydroxybenzylphosphonate), 2,4-dihydroxybenzophenone, 2-(2-hydroxy-3-tert-butyl-5-methylphenyl)-2H-benzotriazole, nickel butylamine complex with 2,2'-thiobis(4-tert-butylphenol), 2-ethoxy-2'-ethyloxanilide or 2-ethoxy-2'-ethyl-5,5'-di-tert-butyloxanilide.

The stabilized polyolefin compositions of the instant invention may also contain other additives such as the pigments, colorants or dyes, light stabilizers such as metal deactivators, talc and other fillers, etc.

In general, the hydroxylamine stabilizers of this invention are employed from about 0.01 to about 5% by weight of the stabilized composition, although this will vary with the particular substrate and application. An advantageous range is from about 0.025 to about 2%, and especially 0.05 to about 1%.

The hydroxylamine compounds of this invention stabilize polyolefins especially during high temperature processing with relatively little change in color, even though the polymer may undergo a number of extrusions.

The instant stabilizers may readily be incorporated into the polyolefins by conventional techniques, at any convenient stage prior to the manufacture of shaped articles therefrom. For example, the stabilizer may be mixed with the polymer in dry powder form, or a suspension or emulsion of the stabilizer may be mixed with a solution, suspension, or emulsion of the polymer. The stablized polyolefin compositions of the invention may optionally also contain from about 0.01 to about 5%, preferably from about 0.025 to about 2%, and especially from about 0.1% to about 0.05%, by weight of various conventional additives, such as the following, or mixtures thereof:

The following may be mentioned as examples of further additives that can be used in the instant compositions.

Metal deactivators, e.g., oxanilide, isophthalic acid dihydrazide, sebacic acid-bis-phenylhydrazide, bis-benzylideneoxalic acid dihydrazide, N,N'-diacetal-adipic acid dihydrazide, N,N'-bis-salicyloyl-oxalic acid dihydrazide, N,N'-bis-salicyloylhydrazine, N,N'-bis-(3,5-di-tert.-butyl-4-hydroxyphenylpropionyl)hydrazine, N-salicyloyl-N'-salicylalhydrazine, 3-salicyloyl-amino-1,2,4-triazole or N,N'-bis-salicyloyl-thiopropionic acid dihydrazide.

Nucleation agents, e.g., 4-tert.-butylbenzoic acid, adipic acid, diphenylacetic acid or substituted sorbitols such as 1,3; 2,4-dibenzylidenesorbitol.

Other additives that can be incorporated in the stabilized compositions are antiblocking agents, clarifiers, antiozonants, lubricants such as stearyl alcohol, fillers, carbon black, asbestos, kaolin, talc, glass fibers, pigments, optical brighteners, flameproofing agents and antistatic agents.

While the stabilizers of this invention may be conveniently incorporated by conventional techniques into polyolefins before the fabrication thereof into shaped articles, it is also possible to apply the instant stabilizers by a topical application to the finished articles. This is particularly useful with fiber applications where the instant stabilizers are applied topically to the fibers, for example, by way of a spin finish during the melt spinning process.

The following examples are presented for the purpose of illustration only and are not to be construed to limit the nature of scope of the instant invention in any manner whatsoever.

EXAMPLE 1 N,N-Bis[3,5-di-tert-butyl-4-hydroxyphenyl)thiomethyl]hydroxylamine

To a stirred suspension of 3.47 g of hydroxylamine hydrochloride in 20 ml of methanol at 0° C. is added a solution of 3.07 g of potassium hydroxide in 50 ml of methanol. Aqueous formaldehyde solution (37%, 8.2 ml) is then added followed by a solution of 23.84 g of 3,5-di-tert-butyl-4-hydroxythiophenol in 100 ml of methanol. The reaction mixture is stirred at ambient temperature for 8 hours followed by addition of 75 ml of water. The precipitated product is removed by filtration and recrystallized from heptane to give 19.5 g of a white solid, m.p. 135°-138° C.

Analysis: Calcd for C₃₀ H₄₇ NO₃ S₂ : C, 67.5; H, 8.9; N, 2.6. Found: C, 67.7; H, 8.8; N, 2.5.

EXAMPLE 2 N,N-Bis[(3,5-di-tert-butyl-4-hydroxybenzyl)thiomethyl]hydroxylamine

The procedure of Example 1 is repeated using 3.47 grams of hydroxylamine hydrochloride, 3.09 grams of potassium hydroxide, 8.20 ml of 37% aqueous formaldehyde, and 26.84 grams of 3,5-di-tert-butyl-4-hydroxybenzyl mercaptan. The reaction product is recrystallized from isopropanol to give 19.96 grams of a white solid, m.p. 98°-101° C.

Analysis: Calcd for C₃₂ H₅₁ NO₃ S₂ : C, 68.4; H, 9.1; N, 2.5. Found: C, 68.1; H, 9.4; N, 2.6.

EXAMPLE 3 N,N-Bis[(3-methyl-5-tert-butyl-4-hydroxyphenyl)thiomethyl]hydroxylamine

The procedure of Example 1 is repeated using 3.47 grams of hydroxylamine hydrochloride, 3.09 grams of potassium hydroxide, 8.20 ml of 37% aqueous formaldehyde, and 19.63 grams of 3-methyl-5-tert-butyl-4-hydroxythiophenol. The reaction product is recrystallized from ethyl acetate-heptane to give 34.7 grams of a white solid, m.p. 115°-118° C.

Analysis: Calcd for C₂₄ H₃₅ NO₃ S₂ : C, 64.1; H, 7.9; N, 3.1. Found: C, 64.0; H, 7.7; N, 3.1.

EXAMPLE 4 N,N-Bis[n-dodecylthiomethyl]hydroxylamine

The procedure of Example 1 is repeated using 3.50 grams of hydroxylamine hydrochloride, 3.10 grams of potassium hydroxide, 8.20 ml of 37% aqueous formaldehyde, and 24.0 ml of n-dodecyl mercaptan. The reaction product is recrystallized from heptane to give 19.8 grams of a white solid, m.p. 63°-65° C.

Analysis: Calcd for C₂₆ H₅₅ NOS₂ : C, 67.6; H, 12.0; N, 3.0. Found: C, 67.7; H, 12.3; N, 3.2.

EXAMPLE 5 N,N-Bis(n-octadecylthiomethyl)hydroxylamine

The above-named compound is prepared using the general procedure of Example 4 when an equivalent amount of n-octadecyl mercaptan is substituted for n-dodecyl mercaptan.

EXAMPLE 6 N,N-Bis(tridecylthiomethyl)hydroxylamine

The above-named compound is prepared using the general procedure of Example 4 when an equivalent amount of tridecyl mercaptan is substituted for n-dodecyl mercaptan.

Analysis: Calcd for C₂₈ H₅₉ NOS₂ : C, 68.9; H, 12.1; N, 2.9. Found: C, 68.6; H, 11.9; N, 2.7.

EXAMPLE 7 N,N-Bis[1-(n-dodecylthio)butyl]hydroxylamine

The above-named compound is prepared using the general procedure of Example 4 when formaldehyde is replaced by an equivalent amount of n-butyraldehyde.

EXAMPLE 8 Processing Stability of Polypropylene at 500° F. (260° C.)

The base formulation comprises 100 parts of unstabilized polypropylene. (Profax 6501, Himont) with 0.10 parts of calcium stearate. The test stabilizers are solvent blended onto the polypropylene from solutions in methylene chloride. After removal of the solvent by evaporation under reduced pressure, the stabilized resin formulation is extruded at 100 rpm from a 1 inch (2.54 cm) diameter extruder under the following extruder conditions:

    ______________________________________                                                          Temperature                                                   Extruder Location  °F.                                                                             °C.                                          ______________________________________                                         Cylinder #1        450     232                                                 Cylinder #2        475     246                                                 Cylinder #3        500     260                                                 Gate #1            500     260                                                 Gate #2            500     260                                                 Gate #3            500     260                                                 ______________________________________                                    

After each of the first, third and fifth extrusions, resin pellets are compression molded into 125 mil (3.2 mm) thick plaques at 380° F. (193° C.) and specimen yellowness index (YI) is determined according to ASTM D1925. Low YI values indicate less yellowing.

Results are seen in Table I.

It is clear from the data in Table I that the presence of the bis(substituted thioalkyl)hydroxylamine in the polypropylene composition containing a phenolic antioxidant essentially eliminates most of the color formation associated with the presence of the phenolic antioxidant.

                  TABLE I                                                          ______________________________________                                         Processing Stability of Polypropylene at 500° F. (260° C.)                  Conc.  Yellowness Index                                                        Stabilizer                                                                            Color After Extrusion                                        Stabilizer*  % by wt. 1         3     5                                        ______________________________________                                         Base formulation                                                                            --       2.1       4.2   6.4                                      Antioxidant A                                                                               0.1      6.0       10.6  14.4                                     Antioxidant A plus                                                                          0.1                                                               Compound of  0.05     5.0       6.2   7.5                                      Example 2                                                                      Compound of  0.05     6.7       8.4   9.2                                      Example 3                                                                      Compound of  0.05     5.4       7.3   8.5                                      Example 4                                                                      ______________________________________                                          *Antioxidant A = neopentanetetrayl                                             tetrakis(3,5di-tert-butyl-4-hydroxyhydrocinnamate)                       

EXAMPLE 9

Unstabilized polypropylene (Profax 6501, Himont) containing 0.1 parts of calcium stearate is throughly blended with 0.1% by weight of neopentanetetrayl tetrakis(3,5-di-tert-butyl-4-hydroxyhydrocinnamate). Also prepared are samples of polypropylene with the same phenolic antioxidant (0.1% by weight) and 0.3% by weight of the compound of Example 3. The blended materials are then milled on a two-roll mill at 182° C. for 10 minutes, after which time the stabilized polypropylene is sheeted from the mill and allowed to cool.

The milled polyprolyene sheets are then cut into pieces and pressed for 7 minutes on hydraulic press at 218° C., 19.25 Kg/cm² pressure. The resulting plaques of 0.635 mm thickness are tested for resistance to accelerated aging in a forced draft oven at 150° C. When the plaques show the first signs of decomposition (e.g., cracking or brown edges), they are considered to have failed. The results are shown in table below.

    ______________________________________                                         Oven Aging Polypropylene Plaques                                               % Stabilizer   Hours to Failure                                                ______________________________________                                         none            3                                                              0.1% phenolic  600                                                             antioxidant*                                                                   0.1% phenolic  900                                                             antioxidant plus                                                               0.3% compound                                                                  of Example 3                                                                   ______________________________________                                          *phenolic antioxdant is named above.                                     

The instant compound of Example 3 is an effective thiosynergist for the phenolic antioxidant in protecting polypropylene.

EXAMPLE 10 Inhibition of Oxidation of Petroleum Turbine Oil

This test is performed according to ASTM procedure D 943-81.

300 ml of 150N paraffinic mineral oil containing 0.25% by weight of the test compound and 60 ml of distilled water are charged into a large glass tube and heated by an oil bath maintained at 95° C. Oxygen is bubbled at a rate of 3 liters per hour through the delivery tube and through the oil-water mixture. Iron-copper catalyst coils are mounted in the oxygen delivery tube. Samples of oil are removed periodically and the acid number determined. The oil under test is considered to have failed when an acid number of 2.0 has been attained. The test data are given below.

    ______________________________________                                         Test Compound    Time    Acid                                                  of Example       Hours   Number                                                ______________________________________                                         Base Oil         <30     2.0                                                   (no stabilizer)                                                                4                 270    2.0                                                   ______________________________________                                    

The instant compound of Example 4 stabilized the oil for a period considerably in excess of the oxidation lifetime of the base oil.

EXAMPLE 11

When a substrate selected from the group consisting of ABS resins, IPS (impact polystyrene), polybutadiene, polyisoprene, natural rubber, poly(phenylene oxide), hydrocarbon lubricating oils and synthetic oils contains in an effective amount a compound of instant Example 1, 2, 3 or 4, the substrate is stabilized against degradation compared to the unstabilized substrate. 

What is claimed is:
 1. A compound of formula I ##STR6## wherein R₁ and R₂ are independently ##STR7## R₄ and R₅ are independently alkyl of 1 to 18 carbon atoms, cycloalkyl of 5 to 6 carbon atoms, phenyl, alkaryl of 7 to 18 carbon atoms or aralkyl of 7 to 9 carbon atoms, and R₃ is hydrogen or alkyl of 1 to 12 carbon atoms.
 2. A compound according to claim 1 wherein R₁ and R₂ are each the same; and R₃ is hydrogen.
 3. A compound according to claim 1 wherein R₄ and R₅ are each the same and are branched chain alkyl of 4 to 8 carbon atoms.
 4. A compound according to claim 3 wherein R₄ and R₅ are each tert-butyl.
 5. The compound according to claim 1 which is N,N-bis[(3,5-di-tert-butyl-4-hydroxyphenyl)thiomethyl]hydroxylamine.
 6. The compound according to claim 1 which is N,N-bis[(3,5-di-tert-butyl-4-hydroxybenzyl)thiomethyl]hydroxylamine.
 7. The compound according to claim 1 which is N,N-bis[(3-methyl-5-tert-butyl-4-hydroxyphenyl)thiomethyl]hydroxylamine.
 8. A composition, stabilized against degradation, which comprises(a) a material subject to oxidative, thermal or light-induced degradation, and (b) a stabilizing amount of a compound of formula A ##STR8## wherein T₁ and T₂ are indpendently alkyl of 1 to 18 carbon atoms, cycloalkyl of 5 to 6 carbon atoms, phenyl, alkaryl of 7 to 18 carbon atoms, aralkyl of 7 to 9 carbon atoms or ##STR9## where T₄ and T₅ are independently alkyl of 1 to 12 carbon atoms, cycloalkyl of 5 to 6 carbon atoms, phenyl, alkaryl of 7 to 18 carbon atoms or aralkyl of 7 to 9 carbon atoms; orT₁ and T₂ together are alkylene of 2 to 3 carbon atoms; and T₃ is hydrogen or alkyl of 1 to 12 carbon atoms.
 9. A composition according to claim 8 wherein the material of component (a) is selected from the group consisting of acrylonitrile-butadiene-styrene (ABS) resins, impact polystyrene, poly(phenylene oxide), polybutadiene, polyisoprene, natural rubber and lubricating oils.
 10. A composition according to claim 8 which comprises(a) a saturated polyolefin or mixture thereof, (b) a stabilizing amount of a stabilizer or mixture of stabilizers selected from the group consisting of the phenolic antioxidants, the hindered amine light stabilizers, the alkylated hydroxybenzoate light stabilizers, the ultraviolet light absorbers, the organic phosphorus compounds, the alkaline metal salts of fatty acids and the thiosynergists, and (c) a stabilizing amount of a hydroxylamine, or mixture of said hydroxylamines, of formula A.
 11. A composition according to claim 10 wherein component (a) is a polyolefin which is a homopolymer or copolymer of an alpha-olefin.
 12. A composition according to claim 11 wherein the polyolefin is selected from the group consisting of polypropylene, low density polyethylene, medium density polyethylene, high density polyethylene, linear low density polyethylene, poly(butene-1), ethylene/vinyl acetate copolymer, ethylene/propylene copolymer, and copolymers of ethylene or of propylene with other alpha-olefins.
 13. A composition according to claim 12 wherein the polyolefin is polypropylene, high density polyethylene, ethylene/propylene copolymer or a copolymer of ethylene or of propylene with another alpha-olefin.
 14. A composition according to claim 8 wherein component (c) is a hydroxylamine derivative of formula A wherein T₁ and T₂ are each the same; and T₃ is hydrogen.
 15. A composition according to claim 8 where in component (c) T₁ and T₂ are the same and are alkyl of 12 to 18 carbon atoms or ##STR10## where T₄ and T₅ are each the same and are branched chain alkyl of 4 to 8 carbon atoms.
 16. A composition according to claim 15 wherein T₄ and T₅ are each tert-butyl.
 17. A composition according to claim 8 wherein the hydroxylamine of formula A is N,N-bis[(3,5-di-tert-butyl-4-hydroxyphenyl)thiomethyl]hydroxylamine, N,N-bis[(3,5-di-tert-butyl-4-hydroxybenzyl)thiomethyl]hydroxylamine, N,N-bis[(3-methyl-5-tert-butyl-4-hydroxyphenyl)thiomethyl]hydroxylamine or N,N-bis(n-dodecylthiomethyl)hydroxylamine.
 18. A composition according to claim 10 wherein component (b) is a phenolic antioxidant in combination with an alkaline metal salt of a fatty acid.
 19. A composition according to claim 10 wherein the phenolic antioxidant is selected from the group consisting of n-octadecyl 3,5-di-tert-butyl-4-hydroxyhydrocinnamate, neopentanetetrayl tetrakis(3,5-di-tert-butyl-4-hydroxyhydrocinnamate), di-n-octadecyl 3,5-di-tert-butyl-4-hydroxybenzylphosphonate, 1,3,5-tris(3,5-di-tert-butyl-4-hydroxybenzyl)isocyanurate, thiodiethylene bis(3,5-di-tert-butyl-4-hydroxyhydrocinnamate), 1,3,5-trimethyl-2,4,6-tris(3,5-di-tert-butyl-4-hydroxybenzyl)benzene, 3,6-dioxaoctamethylene bis(3-methyl-5-tert-butyl-4-hydroxyhydrocinnamate), 2,6-di-tert-butyl-p-cresol, 2,2'-ethylidene-bis(4,6-di-tert-butylphenol), 1,3,5-tris(2,6-dimethyl-4-tert-butyl-3-hydroxybenzyl)isocyanurate, 1,1,3-tris(2-methyl-4-hydroxy-5-tert-butylphenyl)butane, 1,3,5-tris[2-(3,5-di-tert-butyl-4-hydroxyhydrocinnamoyloxy)-ethyl]isocyanurate, 3,5-di-(3,5-di-tert-butyl-4-hydroxybenzyl)mesitol, hexamethylene bis(3,5-di-tert-butyl-4-hydroxyhydrocinnamate), 1-(3,5-di-tert-butyl-4-hydroxyanilino)-3,5-di(octylthio)-s-triazine, N,N'-hexamethylene-bis(3,5-di-tert-butyl-4-hydroxyhydrocinnnamamide), calcium bis(ethyl-3,5-di-tert-butyl-4-hydroxybenzylphosphonate), ethylene bis[3,3-di(3-tert-butyl-4-hydroxyphenyl)butyrate], octyl 3,5-di-tert-butyl-4-hydroxybenzylmercaptoacetate, bis(3,5-di-tert-butyl-4-hydroxyhydrocinnamoyl)hydrazide, and N,N'-bis[2-(3,5-tert-butyl-4-hydroxyhydrocinnamoyloxy)ethyl]oxamide.
 20. A composition according to claim 19 wherein the phenolic antioxidant is neopentanetetrayl tetrakis(3,5-di-tert-butyl-4-hydroxyhydrocinnamate), n-octadecyl 3,5-di-tert-butyl-4-hydroxyhydrocinnamate, 1,3,5-trimethyl-2,4-6-tris(3,5-di-tert-butyl-4-hydroxybenzyl)benzene, 1,3,5-tris(3,5-di-tert-butyl-4-hydroxybenzyl)isocyanurate, 2,6-di-tert-butyl-p-cresol or 2,2'-ethylidene-bis(4,6-di-tert-butylphenol).
 21. A composition according to claim 10 wherein the alkaline metal salt is calcium stearate, zinc stearate, magnesium behenate, sodium ricinoleate or potassium palmitate.
 22. A composition according to claim 21 wherein the alkaline metal salt is calcium stearate.
 23. A compound of formula A ##STR11## wherein T₁ and T₂ are independently alkyl of 8 to 18 carbon atoms, andT₃ is hydrogen or alkyl of 1 to 12 carbon atoms.
 24. A compound according to claim 23 wherein T₁ and T₂ are each the same and are alkyl of 12 to 18 carbon atoms, and T₃ is hydrogen or alkyl of 1 to 4 carbon atoms.
 25. The compound according to claim 23 which is N,N-bis(n-dodecylthiomethyl)hydroxylamine.
 26. The compound according to claim 23 which is N,N-bis(n-octadecylthiomethyl)hydroxylamine.
 27. The compound according to claim 23 which is N,N-(tridecylthiomethyl)hydroxylamine.
 28. The compound according to claim 23 which is N,N-bis[1-(n-dodecylthio)butyl]hydroxylamine. 